The present invention relates to a semiconductor device and a method of manufacturing the same and, more particularly, to a semiconductor device and a method of manufacturing the same, which can improve the reliability and the like of the gate insulating film of a MOS semiconductor device.
Recently, in a device using a gate oxide film as a tunnel oxide film, represented by an electrically programmable and erasable nonvolatile semiconductor memory (EEPROM), a high electric field of 10 MV/cm or more has been applied to the gate oxide film to write and erase data. Higher electric fields tend to be applied to the gate oxide film of a logic operation device to maintain high performance with advances in micropatterning. When the above high electric field is applied to the gate oxide film, electrons gaining high energy from the electric field pass through the gate oxide film. For this reason, high dielectric breakdown strength is required for the gate oxide film.
An empirical method of setting conditions has been used. More specifically, various oxide films are formed first while parameters such as a film formation temperature and a film formation atmosphere are variously changed. The electrical characteristics of the formed films are then evaluated to use conditions that meet the required specifications. With the current trend toward thinner gate oxide films, however, it is difficult to meet the above specifications. In addition, with the current trend toward a larger number of types of products and faster change of generations, the above empirical method of setting conditions is very inefficient. This leads to a serious problem of an increase in product cost.
As described above, although high dielectric breakdown strength is required for the tunnel insulating film of a nonvolatile memory and the gate insulating film of a logic operation device, it is very difficult to meet satisfactory specifications, resulting in a deterioration of the reliability of the device.
A gate oxide film having a thickness of 5 nm or less is required for a transistor used for a logic operation device to attain a reduction in power consumption.
To meet such requirements, i.e., to improve the reliability of a gate oxide film, e.g., to increase the dielectric breakdown strength, it is taken for granted that introduction of fluorine (F) atoms into the gate oxide film is effective. If, however, F atoms are excessively implanted into the gate oxide film, the number of electron traps increases, resulting in a deterioration in the reliability of the device.